Economical engineering training

As this is intended to save you money, buy only the materials you are sure you will need. If you run out, buy more. It is only more cost-effective to gather your own materials rather than buying them if you make very little gold per hour (for example, if your main source of income are dailies or a gathering profession). Avoid having extras, but if you do, try to sell them back on the Auction House.

If you don't have Goblin Engineering, you can substitute Saronite Razorheads at only 2 Saronite Bars each. Once at 445, you can make your class headpiece (example, Truesight Ice Blinders) for 1 skill up point. This is trainable at 440 but is one of the few yellow recipes beyond 445, and you will probably want to make one anyway. Then keep making (depending on available gems) Heartseeker Scopes or Gnomish Army Knives until 450.